Golf club head

ABSTRACT

A golf club head having a hollow structure and including a face, a body, and a weight portion is provided. The body includes a crown, a sole, and a hosel chamber. The crown, the sole, and the hosel chamber include laminated layers of a fiber-reinforced resin. The weight portion is formed of a material having a specific gravity greater than specific gravities of the crown and of the sole. The head volume is greater than or equal to 450 cc and less than or equal to 470 cc. The head weight is less than or equal to 200 g. The average thickness of each of the crown and the sole is greater than or equal to 0.7 mm. The weight of the weight portion is greater than or equal to 20 g, and the weight portion is attached to one or both of the crown and the sole.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based on and claims priority to Japanese Patent Application No. 2020-121409, filed on Jul. 15, 2020, and Japanese Patent Application No. 2020-121410, filed on Jul. 15, 2020, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The disclosures herein relate to a golf club head.

2. Description of the Related Art

Conventionally, wood-type golf club heads including crowns, faces, and soles are known. Such a golf club head may be formed solely of a metallic material such as titanium. A wood-type golf club head that is formed of a metallic material and a fiber-reinforced resin (namely partially formed of a fiber-reinforced resin) has also been proposed.

A golf club head that is at least partially formed of a fiber-reinforced resin can be reduced in weight, increased in volume, and so on as compared to a golf club head formed solely of a metallic material. Therefore, the golf club head at least partially formed of a fiber-reinforced resin can provide a greater degree of freedom in design in many ways than a golf club head formed solely of a metallic material.

However, it is difficult to decrease the weight of and increase the volume of the golf club head while also improving ball striking performance. RELATED-ART DOCUMENTS

PATENT DOCUMENTS

-   Patent Document 1: Japanese Patent No. 5459432

SUMMARY OF THE INVENTION

According to an aspect of the present disclosure, a golf club head having a hollow structure is provided. The golf club head includes a face, a body, and a weight portion. The body includes at least a crown, a sole, and a hosel chamber. The crown, the sole, and the hosel chamber include laminated layers of a fiber-reinforced resin. The weight portion is formed of a material having a specific gravity greater than specific gravities of the crown and of the sole, and is disposed inward relative to a head shell. The head volume is greater than or equal to 450 cc and less than or equal to 470 cc. The head weight is less than or equal to 200 g. The average thickness of each of the crown and the sole is greater than or equal to 0.7 mm. The weight of the weight portion is greater than or equal to 20 g, and the weight portion is attached to one or both of the crown and the sole.

According to another aspect of the present disclosure, a golf club head having a hollow structure is provided. The golf club head includes a face, a body, and a weight portion. The body includes at least a crown, a sole, and a hosel chamber. The crown, the sole, and the hosel chamber include laminated layers of a fiber-reinforced resin. The weight portion is formed of a material having a specific gravity greater than specific gravities of the crown and of the sole, and is disposed inward relative to a head shell. The head volume is greater than or equal to 450 cc and less than or equal to 470 cc. The head weight is less than or equal to 180 g. The average thickness of each of the crown and the sole is greater than or equal to 0.7 mm. The weight of the weight portion is greater than or equal to 10 g, and the weight portion is attached to one or both of the crown and the sole.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects and further features of the present invention will be apparent from the following detailed description when read in conjunction with the accompanying drawings, in which:

FIG. 1 is a perspective view of a golf club head 1 according to a first embodiment;

FIG. 2 is an exploded perspective view of the golf club head 1 according to the first embodiment;

FIG. 3 is a plan view of the golf club head 1 according to the first embodiment;

FIG. 4 is a front view of a body of the golf club head 1 according to the first embodiment;

FIG. 5 is a partially enlarged cross-sectional view of the golf club head 1 according to the first embodiment;

FIG. 6 is a perspective view of a golf club head 1A according to a second embodiment;

FIG. 7 is an exploded perspective view of the golf club head 1A according to the second embodiment;

FIG. 8 is a plan view of the golf club head 1A according to the second embodiment;

FIG. 9 is a front view of a body of the golf club head 1A according to the second embodiment;

FIG. 10 is a partially enlarged cross-sectional view of the golf club head 1A according to the second embodiment;

FIG. 11 is a plan view of a golf club head 1B according to a third embodiment;

FIG. 12 is a front view of the body of the golf club head 1B according to the third embodiment;

FIG. 13 is a plan view of a golf club head 1C according to a fourth embodiment;

FIG. 14 is a front view of the body of the golf club head 1C according to the fourth embodiment;

FIG. 15 is a perspective view of a golf club head 1D according to a fifth embodiment;

FIG. 16 is a perspective view of the body of the golf club head 1D according to the fifth embodiment;

FIG. 17 is a perspective view of a metal hosel 27;

FIG. 18 is a diagram illustrating a variable shaft adjustability mechanism;

FIG. 19 is a perspective view of a golf club head 1E when viewed from the bottom side according to a sixth embodiment;

FIG. 20 is a front view of the body of the golf club head 1E according to the sixth embodiment;

FIG. 21 is a cross-sectional view (part 1) of the golf club head 1E according to the sixth embodiment;

FIG. 22 is a cross-sectional view (part 2) of the golf club head 1E according to the sixth embodiment;

FIG. 23 is a plan view of a golf club head 1F according to a seventh embodiment;

FIG. 24 is a partially enlarged view of the golf club head 1F when viewed from the inner surface of a crown 21 according to the seventh embodiment;

FIG. 25 is a diagram illustrating a specific configuration of rigidity control portions of the crown 21;

FIG. 26 is a bottom view of the golf club head 1F according to the seventh embodiment;

FIG. 27 is a front view of the body of the golf club head 1F according to the seventh embodiment;

FIG. 28 is an exploded perspective view of a golf club head 1G according to an eighth embodiment; and

FIG. 29 is an exploded perspective view of a golf club head 1H according to the eighth embodiment.

DESCRIPTION OF THE EMBODIMENTS

According to an aspect of the present disclosure, a golf club head at least partially formed of a fiber-reinforced resin can be reduced in weight and increased in volume while also improving ball striking performance.

In the following, embodiments of the present invention will be described with reference to the accompanying drawings. In the drawings, the same elements are denoted by the same reference numerals and a duplicate description thereof may be omitted.

First Embodiment

FIG. 1 is a perspective view of a golf club head 1 according to a first embodiment. FIG. 2 is an exploded perspective view of the golf club head 1 according to the first embodiment. In FIG. 1, the double-headed arrow d₁ indicates the “toe-heel” (left-right) direction, namely, the direction from the toe side to the heel side or the direction from the heel side to the toe side, of the golf club head 1, the double-headed arrow d₂ indicates the “crown-sole” (up-down) direction, namely, the direction from the crown side to the sole side or the direction from the sole side to the crown side, of the golf club head 1, and the double-headed arrow d₃ indicates the “face-back” (front-rear) direction, namely, the direction from the face side to the back side or the direction from the back side to the face side, of the golf club head 1.

The golf club head 1 depicted in FIG. 1 and FIG. 2 is a wood-type golf club head such as a driver club head. The golf club head 1 includes a face 10 and a body 20, and has a hollow structure in which the face 10 is joined to and integrated with the body 20.

The body 20 has an opening 201 on the face side of the golf club head 1. A step, on which the face 10 is positioned, is formed on the outer periphery of the opening 201 of the body 20. The face 10 is fitted to the step and joined to the body 20 so as to close the opening 201. Note that the surface inside the hollow structure may be referred to as an inner surface, and the surface outside the hollow structure may be referred to as an outer surface.

The face 10 has a face surface 10 f, which serves as a ball-striking surface. The face 10 has a predetermined thickness, and the face surface 10 f forms the outer surface of the face 10. The face 10 may be formed of titanium, a titanium alloy, stainless steel, aluminum, an aluminum alloy, a ferrous metal, magnesium, a magnesium alloy, or the like.

The face 10 may be formed of a fiber-reinforced resin. The fiber-reinforced resin is a composite material of a resin and fibers to serve as a reinforcing member. Examples of the fibers constituting the fiber-reinforced resin include carbon fibers, glass fibers, aramid fibers, polyethylene fibers, Zyron®, and boron fibers. Examples of the resin constituting the fiber-reinforced resin include epoxy resins, phenolic resins, polyester resins, and polycarbonate resins. For example, the face 10 can be formed of a carbon fiber-reinforced resin.

The body 20 includes a crown 21, a sole 22, and a hosel chamber 23. The crown 21 defines a top portion of the golf club head 1. The sole 22 defines a bottom portion of the golf club head 1. The hosel chamber 23 houses a hosel to which a shaft is coupled. A back end 25 is of the body 20 located on the opposite side from the face 10, and is a portion by which the crown 21 and the sole 22 are connected.

In the body 20, at least the crown 21, the sole 22, and the hosel chamber 23 may be formed by laminating layers of a fiber-reinforced resin. The crown 21, the sole 22, and the hosel chamber 23 may be integrally formed by laminating layers of a fiber-reinforced resin. For example, the crown 21, the sole 22, and the hosel chamber 23 can be formed by laminating layers of a carbon fiber-reinforced resin. Note that if the face 10 is formed of a fiber-reinforced resin, the crown 21, the sole 22, and the hosel chamber 23 may be formed of the same fiber-reinforced resin as the face 10.

FIG. 3 is a plan view of the golf club head 1 according to the first embodiment. FIG. 4 is a front view of the body of the golf club head according to the first embodiment. FIG. 5 is a partially enlarged cross-sectional view of the golf club head 1 according to the first embodiment. FIG. 5 depicts a cross section of the golf club head 1 taken in a plane parallel to a horizontal ground plane.

As illustrated in FIG. 3 through FIG. 5, the golf club head 1 includes a weight portion 70 in the vicinity of the back end 25 of the crown 21 and/or the sole 22. The weight portion 70 is disposed to extend from the toe side to the heel side in the toe-heel direction, and is disposed on the back end 25 side in the face-back direction. For example, the weight portion 70 is disposed such that the weight on the toe side of the weight portion 70 is approximately equal to the weight on the heel side of the weight portion 70.

In the golf club head 1, the weight portion 70 is attached to the crown 21 and/or the sole 22. That is, the weight portion 70 may be provided on the crown 21 or may be provided on the sole 22. Alternatively, the weight portion 70 may be provided across the crown 21 and the sole 22.

The body 20 is formed of a fiber-reinforced resin 251. A surface 70 a of the weight portion 70 contacts the fiber-reinforced resin 251, and a surface 70 b of the weight portion 70 contacts a fiber-reinforced resin 252. The fiber-reinforced resin 252 extends along the surface 70 b of the weight portion 70 and contacts the fiber-reinforced resin 251, which forms the inner surface of the crown 21 and/or the inner surface of the sole 22. The fiber-reinforced resin 251 and/or fiber-reinforced resin 252 may have a laminated structure of multiple layers of a fiber reinforcement resin.

As described above, in the golf club head 1, the weight portion 70 is disposed inward relative to a head shell 20 a. The weight portion 70 is sandwiched between adjacent fiber-reinforced resin layers, and is not exposed to the inside of and the outside of the body 20. The surface 70 a of the weight portion 70 contacts the head shell 20 a, which serves as the inner surface of the fiber-reinforced resin 251, and the surface 70 b does not contact the head shell 20 a. At least one layer of the fiber-reinforced resin 252 is provided on the surface 70 b. Note that the head shell 20 a serves as the inner surface of the body 20 when the weight portion 70 is not attached.

The weight portion 70 is formed of a material having a specific gravity greater than specific gravities of the crown 21 and of the sole 22, which are formed of a fiber reinforced resin. Examples of the material of the weight portion 70 include stainless steel, a stainless steel alloy, tungsten, a tungsten alloy, and brass.

The volume of the golf club head 1 (hereinafter may be referred to as a “head volume”) is, for example, greater than or equal to 450 cc and less than or equal to 470 cc, preferably greater than or equal to 450 cc and less than or equal to 465 cc, and more preferably greater than or equal to 455 cc and less than or equal to 460 cc. The weight of the golf club head 1 including the weight portion 70 (hereinafter may be referred to as a “head weight”) is, for example, greater than or equal to 180 g and less than or equal to 200 g. In order to exhibit remarkable effects of the weight portion 70, the weight of the weight portion 70 is preferably 20% or more of the head weight. Specifically, the weight of the weight portion 70 is greater than or equal to 20 g, and preferably greater than or equal to 30 g and less than or equal to 55 g.

The maximum head height of the golf club head 1 is, for example, greater than or equal to 60 mm. The maximum head width of the golf club head 1 is, for example, greater than or equal to 112 mm. The maximum head height of the golf club head 1 is the height from the lowest point of the sole 22 to the highest point of the crown 21 when the golf club head 1 is placed in a reference state. The maximum head width of the golf club head 1 is the width from the leading edge to the maximum protrusion on the back side of the golf club head 1.

For example, a characteristic time (CT), corresponding to the coefficient of restitution of the face 10, of the golf club head 1 is less than or equal to 257 μs. Further, the average thickness of the crown 21 and the average thickness of the sole 22 are both greater than or equal to 0.7 mm. The center-of-gravity angle of the golf club head 1 is, for example, greater than or equal to 25 degrees and less than or equal to 45 degrees. The center-of-gravity distance of the golf club head 1 is, for example, greater than or equal to 35 mm and less than or equal to 45 mm. As used herein, the “average thickness” refers to the average value of the thicknesses at 45 points selected from any 5 points in each of 9 flat areas, where a weight portion or a reinforcing portion (such as a rib or a thick portion) is not formed, obtained by equally dividing each of the crown 21 and the sole 22 into three areas in the face-back direction and in the toe-heel direction.

The golf club head 1 can be manufactured by using a mold assembly and a pressure forming device, for example. The mold assembly can be assembled and disassembled, and the pressure forming device includes an openable sealed container, and a pneumatic mechanism and a heating mechanism installed in the openable sealed container.

Specifically, the golf club head 1 may be manufactured by a method as described below. First, a mold assembly that can be assembled and disassembled is prepared. Then, a plurality of layers of prepregs formed of a fiber-reinforced resin are prepared, and the prepregs are attached to the mold assembly so as to be laminated to form a blank of the body 20.

In order to form the weight portion 70 integrally with a fiber-reinforced resin of the crown 21 and/or the sole 22, the weight portion 70 may be placed within the blank of the body 20 when the blank of the body 20 is formed by attaching the plurality of prepregs to the mold assembly such that the prepregs are laminated. Specifically, the weight portion 70 may be bonded to the prepregs, or the weight portion 70 may be covered by the prepregs.

Next, the mold assembly including the blank of the body 20 is placed into a bag. The bag is placed in the openable sealed container, and heat is applied by the heating mechanism while a vacuum is created by the pneumatic mechanism. In this manner, the prepregs formed of the fiber-reinforced resin, which constitute the blank of the body 20, are cured by a cross-linking reaction. After the heating, the body 20 is bonded to the preformed face 10 to form a semi-finished golf club head. The semi-finished golf club head is deburred and subjected to surface finishing to obtain the golf club head 1.

In the above-described method, when heat is applied by the heating mechanism while a vacuum is created by the pneumatic mechanism, the vacuum pressure value can be set in a range from −0.1 mbar to −1000 mbar, the heating temperature can be set in a range from 40° C. to 250° C., and the vacuum treatment and heating time can be set in a range from 1 minute to 60 minutes.

An autoclave may be used as the pressure forming device. If an autoclave is used as the pressure forming device, the autoclave is able to heat, evacuate air, and apply positive air pressure to a blank of the golf club head 1. For example, a positive air pressure value may be set in a range from 2 bar to 100 bar.

Further, the vacuum, the heating temperature, and the positive air pressure may be adjusted in accordance with the shape of a wood-type golf club head, the thickness of prepregs formed of a fiber-reinforced resin, or the like. Further, the vacuum pressure value, the heating temperature, and the positive air pressure value may also be adjusted in accordance with the cross-linking reaction of prepregs formed of a fiber-reinforced resin. That is, the shape and weight of a golf club head can be readily controlled by using a fiber-reinforced resin as the material of the body.

Table 1 and Table 2 below indicate examples of function values of conventional golf club head (driver club head) models recently put on the market. Note that although the weight of model F is as light as 182.8 g, this model is designed for senior citizen use. The values in Table 1 and Table 2 are obtained by actually measuring the conventional golf club heads.

TABLE 1 FUNCTION MODEL MODEL MODEL MODEL MODEL MODEL VALUE A B C D E F HEAD 201.2 196.0 193.2 201.8 199.2 182.8 WEIGHT [g] CENTER-OF- 33.7 34.2 38.4 33.0 39.0 34.7 GRAVITY DEPTH [mm] MOMENT OF 4489.0 3925.0 4846.0 4309.0 4845.0 3832.0 INERTIA Y [g · cm²] CENTER-OF- 39.3 47.0 51.3 42.3 46.8 38.9 GRAVITY DISTANCE [mm] CENTER-OF- 28.0 22.0 28.0 25.0 29.0 33.0 GRAVITY ANGLE [DEGREE] HEAD 441.0 458.0 453.0 456.0 462.0 446.0 VOLUME [cc]

TABLE 2 FUNCTION MODEL MODEL MODEL MODEL MODEL MODEL VALUE G H I J K L HEAD 202.7 194.8 193.9 202.6 195.0 194.1 WEIGHT [g] CENTER-OF- 32.8 34.5 38.4 40.5 32.9 30.6 GRAVITY DEPTH [mm] MOMENT OF 4437.0 4464.0 4647.0 5439.0 4398.0 3869.0 INERTIA Y [g · cm²] CENTER-OF- 41.1 46.8 47.7 57.4 42.6 36.5 GRAVITY DISTANCE [mm] CENTER-OF- 25.0 26.0 28.0 29.0 26.0 29.0 GRAVITY ANGLE [DEGREE] HEAD 459.0 451.0 456.0 454.0 448.0 454.0 VOLUME [cc]

Conversely, Table 3 indicates examples of function values of the golf club head 1 according to the first embodiment. In Table 3, the moment of inertia X indicates the moment of inertia in the face-back direction, and the moment of inertia Y indicates the moment of inertia in the toe-heel direction. Note that the values in Table 3 are obtained from computer aided design (CAD) data.

In Table 3, the head volume of each of model M and model N is greater than or equal to 450 cc and less than or equal to 470 cc, and the head weight is less than or equal to 200 g. In each of the model M and the model N, even if the head weight is light, sufficiently high moments of inertia can be obtained. Further, although the center-of-gravity distance is 40 mm or less, the moments of inertia are high and the center-of-gravity angle is large.

TABLE 3 FUNCTION MODEL MODEL VALUE M N HEAD 192.0 182.0 WEIGHT [g] WEIGHT OF 45.3 35.3 WEIGHT PORTION [g] CENTER-OF- 39.9 36.9 GRAVITY DEPTH [mm] MOMENT OF 3457.0 3130.0 INERTIA X [g · cm²] MOMENT OF 4819.0 4472.0 INERTIA Y [g · cm²] CENTER-OF- 39.5 38.3 GRAVITY DISTANCE [mm] CENTER-OF- 35.2 31.3 GRAVITY ANGLE [DEGREE] HEAD 455 455 VOLUME [cc]

In the case of titanium driver club heads recently put on the market, the average thickness of a crown is approximately 0.5 mm to 0.7 mm and the average thickness of a sole is approximately 0.8 mm. For such a golf club head, in order to secure additional weight to enable a unique design, it would be required to reduce the weight of a part of the golf club head so as to avoid an increase in the entire head weight. Because the coefficient of restitution of a face is limited by the official rules of golf, reducing the weight of the face would be difficult. Therefore, the weight of the crown or the sole would need to be reduced.

That is, if the weight of the face is reduced by reducing the thickness of the face, the coefficient of resilience of the face would increase due to the reduced thickness. As a result, the CT, corresponding to the coefficient of restitution of the face, would be highly likely to exceed 257 μs, which is the limit on spring-like effect (SLE) set by the Royal and Ancient Golf Club of St Andrews (R&A). For this reason, the weight of the crown or the sole would need to be reduced.

However, for conventional driver club heads, there is a limitation on reducing the thickness of the crown or the sole while securing strength, and thus, it would be difficult to have large additional weight while maintaining certain thicknesses of the crown and the sole. Conversely, in the golf club head 1 according to the first embodiment, because the crown 21, the sole 22, and the hosel chamber 23 are formed by laminating layers of a fiber-reinforced resin, additional weight can be readily secured as compared to the conventional driver club heads.

Specifically, a weight of 20 g or more can be added to the golf club head 1 even when each of the crown 21 and the sole 22 has the average thickness of 0.7 mm or more. That is, a weight of 20 g or more can be added to the weight portion 70. In other words, the weight portion 70 with a weight of 20 g or more can be attached to the crown 21 and/or the sole 22. Accordingly, as can be seen from Table 3, even if the head weight is 200 g or less, the golf club head 1 having a sufficiently large head volume with high moments of inertia can be provided.

The moment of inertia Y is preferably greater than or equal to 4000 g·cm² and less than or equal to 6000 g·cm², and more preferably greater than or equal to 4350 g·cm² and less than or equal to 5200 g·cm². The center-of-gravity angle is preferably greater than or equal to 25 degrees and less than or equal to 45 degrees, and more preferably greater than or equal to 30 degrees and less than or equal to 40 degrees.

Among the conventional golf club heads, a golf club head whose moment of inertia Y per head weight is close to that of the golf club head 1 has a small center-of-gravity angle, and a golf club head whose center-of-gravity angle per head weight is close to that of the golf club head 1 has a low moment of inertia Y. That is, unlike the conventional golf club heads, in the golf club head 1, both the moment of inertia Y per head weight and the center-of-gravity angle per head weight can be largely increased at the same time.

As can be calculated from the functional values indicated in Table 3, a value obtained by dividing the weight of the weight portion 70 by the head weight of the golf club head 1 can be greater than or equal to 0.19 and less than or equal to 0.24. Further, a value obtained by dividing the center-of-gravity distance by the head weight of the golf club head 1 can be greater than or equal to 0.20. Further, a value obtained by dividing the center-of-gravity angle by the head weight of the golf club head 1 can be greater than or equal to 0.17 and less than or equal to 0.19.

Accordingly, in the golf club head 1, because the crown 21, the sole 22, and the hosel chamber 23 are formed by laminating layers of a fiber-reinforced resin, the head weight can be reduced. That is, the golf club head 1 whose head volume is greater than or equal to 450 cc and less than or equal to 470 cc and whose head weight is less than or equal to 200 g can be provided. In addition, the average thickness of each of the crown 21 and the sole 22 can be 0.7 mm or more, thus allowing the strength of each of the crown 21 and the sole 22 to be sufficiently maintained.

Further, in the golf club head 1, the crown 21, the sole 22, and the hosel chamber 23 are integrally formed by laminating layers of a fiber-reinforced resin with a high strength-to-weight ratio, thus allowing additional weight to be readily secured as compared to the conventional golf club heads. Further, the weight portion 70 can be readily provided at any position of the crown 21 and/or the sole 22 by sandwiching the weight portion 70 between adjacent fiber-reinforced resin layers.

Accordingly, various designs using the weight portion 70 are possible. For example, effects of increasing the head speed associated with a reduction in the head weight can be exhibited while also preventing a deterioration in performance due to the reduction in the head weight. As an example, in the golf club head 1, the weight portion 70 is disposed to extend from the toe side to the heel side in the toe-heel direction, and is disposed on the back end 25 side in the face-back direction. In addition, the weight portion 70 is disposed such that the weight on the toe side of the weight portion 70 is approximately equal to the weight on the heel side of the weight portion 70.

Accordingly, although the weight of the golf club head 1 is less than or equal to 200 g, the moments of inertia can be increased, thereby increasing the stability of the head and the straightness of the ball trajectory. As a result, in the golf club head 1, the rotation of the head when mishitting a golf ball can be suppressed and thus slicing can be avoided.

Second Embodiment

In the following, a golf club head 1A according to a second embodiment will be described. In the second embodiment, differences from the first embodiment will be described, and descriptions of elements having the same configuration and functions as those of the first embodiment may be omitted.

FIG. 6 is a perspective view of the golf club head 1A according to the second embodiment. FIG. 7 is an exploded perspective view of the golf club head 1A according to the second embodiment.

The golf club head 1A depicted in FIG. 6 and FIG. 7 is a wood-type golf club head such as a driver club head. The golf club head 1A includes a face 10 and a body 20, and has a hollow structure in which the face 10 is joined to and integrated with the body 20.

The body 20 includes a crown 21, a sole 22, and a hosel chamber 23. In the body 20, at least the crown 21, the sole 22, and the hosel chamber 23 may be formed by laminating layers of a fiber-reinforced resin. The crown 21, the sole 22, and the hosel chamber 23 may be integrally formed by laminating layers of a fiber-reinforced resin. For example, the crown 21, the sole 22, and the hosel chamber 23 can be formed by laminating layers of a carbon fiber-reinforced resin. Note that if the face 10 is formed of a fiber-reinforced resin, the crown 21, the sole 22, and the hosel chamber 23 may be formed of the same fiber-reinforced resin as the face 10.

FIG. 8 is a plan view of the golf club head 1A according to the second embodiment. FIG. 9 is a front view of the body of the golf club head 1A according to the second embodiment. FIG. 10 is a partially enlarged cross-sectional view of the golf club head 1A according to the second embodiment. FIG. 10 depicts a cross section of the golf club head 1A taken in a plane parallel to a horizontal ground plane.

Similar to the first embodiment, as illustrated in FIG. 8 through FIG. 10, the golf club head 1A includes a weight portion 70 in the vicinity of the back end 25 of the crown 21 and/or the sole 22. The weight portion 70 is disposed to extend from the toe side to the heel side in the toe-heel direction, and is disposed on the back end 25 side in the face-back direction. For example, the weight portion 70 is disposed such that the weight on the toe side of the weight portion 70 is approximately equal to the weight on the heel side of the weight portion 70.

In the golf club head 1A, the weight portion 70 is attached to the crown 21 and/or the sole 22. That is, the weight portion 70 may be provided on the crown 21 or may be provided on the sole 22. Alternatively, the weight portion 70 may be provided across the crown 21 and the sole 22.

The body 20 is formed of a fiber-reinforced resin 251. A surface 70 a of the weight portion 70 contacts the fiber-reinforced resin 251, and a surface 70 b of the weight portion 70 contacts a fiber-reinforced resin 252. The fiber-reinforced resin 252 extends along the surface 70 b of the weight portion 70 and contacts the fiber-reinforced resin 251, which forms the inner surface of the crown 21 and/or the inner surface of the sole 22. The fiber-reinforced resin 251 and/or fiber-reinforced resin 252 may have a laminated structure of multiple layers of a fiber reinforcement resin.

As described above, in the golf club head 1, the weight portion 70 is disposed inward relative to a head shell 20 a. The weight portion 70 is sandwiched between adjacent fiber-reinforced resin layers, and is not exposed to the inside of and the outside of the body 20. The surface 70 a of the weight portion 70 contacts the head shell 20 a, which serves as the inner surface of the fiber-reinforced resin 251, and the surface 70 b does not contact the head shell 20 a. The surface 70 b has at least one layer of the fiber-reinforced resin 252. Note that the head shell 20 a serves as the inner surface of the body 20 when the weight portion 70 is not attached.

The weight portion 70 is formed of a material having a specific gravity greater than specific gravities of the crown 21 and of the sole 22, which are formed of a fiber reinforced resin. Examples of the material of the weight portion 70 include stainless steel, a stainless steel alloy, tungsten, a tungsten alloy, and brass.

The volume of the golf club head 1A (hereinafter may be referred to as a “head volume”) is, for example, greater than or equal to 450 cc and less than or equal to 470 cc, preferably greater than or equal to 450 cc and less than or equal to 465 cc, and more preferably greater than or equal to 455 cc and less than or equal to 460 cc. The weight of the golf club head 1A including the weight portion 70 (hereinafter may be referred to as a “head weight”) is, for example, greater than or equal to 160 g and less than or equal to 180 g. In order to exhibit remarkable effects of the weight portion 70, the weight of the weight portion 70 may be greater than or equal to 10 g and less than or equal to 35 g.

The maximum head height of the golf club head 1A is, for example, greater than or equal to 60 mm. The maximum head width of the golf club head 1A is, for example, greater than or equal to 112 mm. The maximum head height of the golf club head 1A is the height from the lowest point of the sole 22 to the highest point of the crown 21 when the golf club head 1A is placed in a reference state. The maximum head width of the golf club head 1A is the width from the leading edge to the maximum protrusion on the back side of the golf club head 1A.

For example, a characteristic time (CT), corresponding to the coefficient of restitution of the face 10, of the golf club head 1A is less than or equal to 257 μs. Further, the average thickness of the crown 21 and the average thickness of the sole 22 are both greater than or equal to 0.7 mm. The center-of-gravity angle of the golf club head 1A is, for example, greater than or equal to 15 degrees and less than or equal to 40 degrees. The center-of-gravity distance of the golf club head 1A is, for example, greater than or equal to 35 mm and less than or equal to 45 mm.

The golf club head 1A according to the second embodiment can be manufactured in the same manner as that described in the first embodiment.

Table 4 below indicates examples of function values of the golf club head 1A according to the second embodiment. In Table 4, the moment of inertia X indicates the moment of inertia in the face-back direction, and the moment of inertia Y indicates the moment of inertia in the toe-heel direction. Note that the values in Table 4 are obtained from CAD data.

In Table 4, the head volume of each of model O and model P is greater than or equal to 450 cc and less than or equal to 470 cc, and the head weight is less than or equal to 180 g. In the conventional golf club heads whose head volumes are approximately 440 cc to 160 cc as indicated in Table 1 and Table 2 above, the head weights are approximately 180 g to 200 g, and no conventional golf club head has a weight as light as 180 g or less. In each of the model O and the model P, even if the head weight is light, sufficiently high moments of inertia can be obtained. In addition, the center-of-gravity depth and center-of-gravity angle indicate values comparable to those of the models A through L each having a weight greater than 180 g. Further, although the center-of-gravity distance is 40 mm or less, the moments of inertia are high and the center-of-gravity angle is large.

TABLE 4 FUNCTION MODEL MODEL VALUE O P HEAD 172.0 162.0 WEIGHT [g] WEIGHT OF 25.3 15.3 WEIGHT PORTION [g] CENTER-OF- 33.5 29.7 GRAVITY DEPTH [mm] MOMENT OF 2761.0 2349.0 INERTIA X [g · cm²] MOMENT OF 4082.0 3649.0 INERTIA Y [g · cm²] CENTER-OF- 37.2 36.4 GRAVITY DISTANCE [mm] CENTER-OF- 26.7 21.5 GRAVITY ANGLE [DEGREE] HEAD 455 455 VOLUME [cc]

In the case of titanium driver club heads recently put on the market, the average thickness of a crown is approximately 0.5 mm to 0.7 mm and the average thickness of a sole is approximately 0.8 mm. For such a golf club head, in order to secure additional weight to enable a unique design, it would be required to reduce the weight of a part of the golf club head so as to avoid an increase in the entire head weight. Because of the coefficient of restitution of a face by the official rules of golf, reducing the weight of the face would be difficult. Therefore, the weight of the crown or the sole would need to be reduced.

That is, if the weight of the face is reduced by reducing the thickness of the face, the coefficient of resilience of the face would increase due to the reduced thickness. As a result, the CT, corresponding to the coefficient of restitution of the face, would be highly likely to exceed 257 μs, which is the limit on spring-like effect (SLE) set by the Royal and Ancient Golf Club of St Andrews (R&A). For this reason, the weight of the crown or the sole would need to be reduced.

However, for conventional driver club heads, there is a limitation on reducing the thickness of the crown or the sole while securing strength, and thus, it would be difficult to have large additional weight while maintaining certain thicknesses of the crown and the sole. Conversely, in the golf club head 1A according to the second embodiment, because the crown 21, the sole 22, and the hosel chamber 23 are formed by laminating layers of a fiber-reinforced resin, additional weight can be readily secured as compared to the conventional driver club heads.

Specifically, a weight of 10 g or more can be added to the golf club head 1A even when each of the crown 21 and the sole 22 has the average thickness of 0.7 mm or more. That is, a weight of 10 g or more can be added to the weight portion 70. In other words, the weight portion 70 with a weight of 10 g or more can be attached to the crown 21 and/or the sole 22. Accordingly, as can be seen from Table 4, even if the head weight is 180 g or less, the golf club head 1A having a sufficiently large head volume with high moments of inertia can be provided.

The moment of inertia Y is preferably greater than or equal to 3000 g·cm² and less than or equal to 4000 g·cm², and more preferably greater than or equal to 3550 g·cm² and less than or equal to 4400 g·cm². The center-of-gravity angle is preferably greater than or equal to 15 degrees and less than or equal to 40 degrees, and more preferably greater than or equal to 20 degrees and less than or equal to 30 degrees.

Among the conventional golf club heads, a golf club head whose moment of inertia Y per head weight is close to that of the golf club head 1A has a small center-of-gravity angle, and a golf club head whose center-of-gravity angle per head weight is close to that of the golf club head 1A has a low moment of inertia Y. That is, unlike the conventional golf club heads, in the golf club head 1A, both the moment of inertia Y per head weight and the center-of-gravity angle per head weight can be largely increased at the same time.

As can be calculated from the functional values indicated in Table 4, a value obtained by dividing the weight of the weight portion 70 by the head weight of the golf club head 1A can be greater than or equal to 0.09 and less than or equal to 0.19. Further, a value obtained by dividing the center-of-gravity distance by the head weight of the golf club head 1A can be greater than or equal to 0.21. Further, a value obtained by dividing the center-of-gravity angle by the head weight of the golf club head 1A can be greater than or equal to 0.13 and less than or equal to 0.17.

Accordingly, in the golf club head 1A, because the crown 21, the sole 22, and the hosel chamber 23 are formed by laminating layers of a fiber-reinforced resin, the head weight can be reduced. That is, the golf club head 1A whose head volume is greater than or equal to 450 cc and less than or equal to 470 cc and whose head weight is less than or equal to 180 g can be provided. In addition, the average thickness of each of the crown 21 and the sole 22 can be 0.7 mm or more, thus allowing the strength of each of the crown 21 and the sole 22 to be sufficiently maintained.

Further, in the golf club head 1A, the crown 21, the sole 22, and the hosel chamber 23 are integrally formed by laminating layers of a fiber-reinforced resin with a high strength-to-weight ratio, thus allowing additional weight to be readily secured as compared to the conventional golf club heads. Further, the weight portion 70 can be readily provided at any position of the crown 21 and/or the sole 22 by sandwiching the weight portion 70 between adjacent fiber-reinforced resin layers.

Accordingly, various designs using the weight portion 70 are possible. For example, effects of increasing the head speed associated with a reduction in the head weight can be exhibited while also preventing a deterioration in performance due to the reduction in the head weight. As an example, in the golf club head 1A, the weight portion 70 is disposed to extend from the toe side to the heel side in the toe-heel direction, and is disposed on the back end 25 side in the face-back direction. In addition, the weight portion 70 is disposed such that the weight on the toe side of the weight portion 70 is approximately equal to the weight on the heel side of the weight portion 70. Accordingly, although the weight of the golf club head 1A is less than or equal to 180 g, the moments of inertia can be increased, thereby increasing the stability of the head and the straightness of the ball trajectory. As a result, in the golf club head 1A, the rotation of the head when mishitting a golf ball can be suppressed and thus slicing can be avoided.

Third Embodiment

A third embodiment depicts an example of a golf club head in which a weight portion is provided at a different position from that of the above-described embodiments. In the third embodiment, descriptions of elements identical to those in the above-described embodiments may be omitted.

FIG. 11 is a plan view of a golf club head 1B according to the third embodiment. FIG. 12 is a front view of the body of the golf club head 1B according to the third embodiment.

As illustrated in FIG. 11 and FIG. 12, the golf club head 1B includes a weight portion 71 in the vicinity of the back end 25 of the crown 21 and/or the sole 22. In the golf club head 1B, the weight portion 71 may be provided on the crown 21 or may be provided on the sole 22. Alternatively, the weight portion 71 may be provided across the crown 21 and the sole 22.

The weight portion 71 is located closer to the heel side than to the toe side in the toe-heel direction, and is located on the back end 25 side in the face-back direction. For example, the weight portion 71 is disposed such that the weight of the weight portion 71 is greater on the heel side than on the toe side.

The volume, the weight, the maximum head height, the maximum head width, the CT, the average thickness of the crown 21, and the average thickness of the sole 22 of the golf club head 1B are similar to those of the golf club head 1. Further, the material and the weight of the weight portion 71 are similar to those of the weight portion 70.

Accordingly, in the golf club head 1B, because the crown 21, the sole 22, and the hosel chamber 23 are formed by laminating layers of a fiber-reinforced resin, the head weight can be reduced. That is, the golf club head 1B whose head volume is greater than or equal to 450 cc and less than or equal to 470 cc and whose head weight is less than or equal to 200 g or less than or equal to 180 g can be provided. In addition, the average thickness of each of the crown 21 and the sole 22 can be 0.7 mm or more, thus allowing the strength of each of the crown 21 and the sole 22 to be sufficiently maintained.

Further, similar to the above-described embodiments, in the golf club head 1B, the crown 21, the sole 22, and the hosel chamber 23 are formed by laminating layers of a fiber-reinforced resin, thus allowing additional weight to be readily secured as compared to the conventional golf club heads. Further, the weight portion 71 can be readily provided at the crown 21 and/or the sole 22 by sandwiching the weight portion 71 between adjacent fiber-reinforced resin layers.

Accordingly, various designs using the weight portion 71 are possible. For example, a deterioration in performance due to a reduction in the head weight can be prevented. As an example, in the golf club head 1B, the weight portion 71 is disposed closer to the heel side than to the toe side in the toe-heel direction, and is disposed on the back end 25 side in the face-back direction. Therefore, in the golf club head 1B, the center-of-gravity angle can be increased, thus improving catchability when striking a golf ball. As a result, slicing can be avoided and a draw can be readily hit.

Fourth Embodiment

A fourth embodiment depicts another example of a golf club head in which a weight portion is provided at a different position from that of the first embodiment. In the fourth embodiment, descriptions of elements identical to those in the above-described embodiments may be omitted.

FIG. 13 is a plan view of a golf club head 10 according to the fourth embodiment. FIG. 14 is a front view of the body of the golf club head 10 according to the fourth embodiment.

As illustrated in FIG. 13 and FIG. 14, the golf club head 10 includes a weight portion 72 in the vicinity of the back end 25 of the crown 21 and/or the sole 22. In the golf club head 1C, the weight portion 72 may be provided on the crown 21 or may be provided on the sole 22. Alternatively, the weight portion 71 may be provided across the crown 21 and the sole 22.

The weight portion 72 is disposed to extend from the toe side to the heel side in the toe-heel direction, and is located on the back end 25 side in the face-back direction. For example, the weight portion 72 is disposed such that the weight of the weight portion 72 is greater on the heel side than on the toe side. That is, the weight portion 72 has a shape as if the weight portion 71 is added to the weight portion 70.

The volume, the weight, the maximum head height, the maximum head width, the CT, the average thickness of the crown 21, and the average thickness of the sole 22 of the golf club head 1C are similar to those of the golf club head 1. Further, the material and the weight of the weight portion 72 are similar to those of the weight portion 70.

Similar to the above-described embodiments, in the golf club head 1C, because the crown 21, the sole 22, and the hosel chamber 23 are formed by laminating layers of a fiber-reinforced resin, the head weight can be reduced. That is, the golf club head 10 whose head volume is greater than or equal to 450 and less than or equal to 470 cc and whose head weight is less than or equal to 200 g or less than or equal to 180 g can be provided. In addition, the average thickness of each of the crown 21 and the sole 22 can be 0.7 mm or more, thus allowing the strength of each of the crown 21 and the sole 22 to be sufficiently maintained.

Further, similar to the above-described embodiments, in the golf club head 1C, the crown 21, the sole 22, and the hosel chamber 23 are formed by laminating layers of a fiber-reinforced resin, thus allowing additional weight to be readily secured as compared to the conventional golf club heads. Further, the weight portion 72 can be readily provided at the crown 21 and/or the sole 22 by sandwiching the weight portion 72 between adjacent fiber-reinforced resin layers.

Accordingly, various designs using the weight portion 72 are possible. For example, a deterioration in performance due to a reduction in the head weight can be prevented. As an example, in the golf club head 1C, the weight portion 72 is disposed to extend from the toe side to the heel side in the toe-heel direction, and is disposed on the back end 25 side in the face-back direction. In addition, the weight portion 72 is disposed such that the weight of the weight portion 72 is greater on the heel side than on the toe side. Accordingly, in the golf club head 1C, although head weight is less than or equal to 200 g or less than or equal to 180 g, the moments of inertia can be increased, thereby increasing the stability of the golf club head 1C and the straightness of the ball trajectory. As a result, in the golf club head 1C, the rotation of the head when mishitting a golf ball can be suppressed and thus slicing can be avoided. Further, in the golf club head 1C, the center-of-gravity angle can be increased, thus improving catchability when striking a golf ball. As a result, slicing can be avoided and a draw can be readily hit.

The golf club heads 1 through 10 can be manufactured by using the same mold assembly. A weight portion may be disposed at any location in a blank of a body. That is, various function values can be achieved by using the same mold assembly and simply changing the size, the weight, or the position of the weight portion. The above-described high moments of inertia and high center-of-gravity angle are merely examples. By using the same mold assembly and simply changing the size, the weight, or the position of the weight portion, various characteristics can be achieved in accordance with the requirements of a golfer, such as a low center of gravity (easiness in hitting high balls and a low spin rate) and a forward center of gravity (a low spin rate and a strong ballistic trajectory). In addition, golf club heads having various characteristics are expected to be used for fitting.

Fifth Embodiment

A fifth embodiment depicts an example of a golf club head in which a metal hosel is attached to the hosel chamber 23. In the fifth embodiment, descriptions of elements identical to those in the above-described embodiments may be omitted.

FIG. 15 is a perspective view of a golf club head 1D according to the fifth embodiment. FIG. 16 is a perspective view of the body of the golf club head 1D according to the fifth embodiment. FIG. 17 FIG. 17 is a perspective view of a metal hosel 27.

As illustrated in FIG. 15 through FIG. 17, in the golf club head 1D, at least the crown 21, the sole 22, and the hosel chamber 23 of the body 20 are formed by laminating layers of a fiber-reinforced resin.

In the golf club head 1D, the hosel chamber 23 extends through the body 20 and to the sole 22. The hosel chamber 23 has a hollow cylindrical shape and houses the metal hosel 27. A large diameter portion on one end side of the metal hosel 27 is exposed from the hosel chamber 23. A portion of the hosel chamber 23 located within the body 20 is cut out to expose the side surface of the metal hosel 27.

The metal hosel 27 may be a member having a hollow cylindrical shape. For example, titanium, a titanium alloy, aluminum, an aluminum alloy, tungsten, a tungsten alloy, stainless steel, or the like may be used as the material of the metal hosel 27. The metal hosel 27 may be integrally formed with the fiber-reinforced resin included in the body 20.

In order to form the metal hosel 27 integrally with the fiber-reinforced resin included in the body 20, the metal hosel 27 may be placed within a blank of the body 20 when the blank of the body 20 is formed by attaching a plurality of prepregs to a mold assembly such that the plurality of prepregs are laminated. Specifically, the metal hosel 27 may be bonded to the prepregs, or the metal hosel 27 may be covered by the prepregs.

In this manner, in the golf club head 1D, at least the crown 21, the sole 22, and the hosel chamber 23 of the body 20 are formed by laminating layers of a fiber-reinforced resin. Therefore, the metal hosel 27 can be readily embedded into the body 20. By embedding the metal hosel 27, the strength of the metal hosel 27 can be enhanced as compared to when a hosel formed of a resin is used.

The golf club head 1D may have a variable shaft adjustability mechanism. The variable shaft adjustability mechanism may include the metal hosel 27, a shaft case 28, and an attachment screw 29 as illustrated in FIG. 18. Specifically, the shaft case 28 is housed within the metal hosel 27 and is removably attached to the metal hosel 27 by the attachment screw 29 from the sole 22 side. For example, the shaft case 28 may be affixed to a shaft with an adhesive.

One or both of a hole of the metal hosel 27 and a hole of the shaft case 28 may be eccentric. Therefore, attaching the shaft case 28 to the metal hosel 27 by causing the shaft case 28 to rotate in a circumferential direction allows the positional relationship between the golf club head 1D and the shaft (for example, a lie angle, a face angle, and the like) to be adjusted.

Accordingly, in the golf club head 10, the crown 21, the sole 22, and the hosel chamber 23 are formed by laminating layers of a fiber-reinforced resin, thus allowing additional weight to be readily secured as compared to the conventional golf club heads. As a result, the additional weight can be added to the metal hosel 27 or the shaft case 28 constituting the variable shaft adjustability mechanism.

Sixth Embodiment

A sixth embodiment depicts an example of a golf club head that includes a connector to which/from which a rod is attachable/detachable. In the sixth embodiment, descriptions of elements identical to those in the above-described embodiments may be omitted.

FIG. 19 is a perspective view of a golf club head 1E when viewed from the bottom side according to the sixth embodiment. FIG. 20 is a front view of the body of the golf club head 1E according to the sixth embodiment. As illustrated in FIG. 19 and FIG. 20, a recessed portion 222 is provided in the sole 22 of the golf club head 1E. The recessed portion 222 is recessed from the outer surface side toward the inner surface side of the sole 22. The recessed portion 222 includes a connector 223 that is made of metal and to which/from which a rod 90 is attachable/detachable. The face 10 is, for example, made of metal, and the face 10 is apart from the connector 223. FIG. 19 and FIG. 20 depict a state in which the rod 90 is not attached to the connector 223.

The connector 223 is formed integrally with a fiber-reinforced resin of the sole 22. In order to form the connector 223 integrally with the fiber-reinforced resin of the sole 22, the connector 223 may be placed within a blank of the body 20 when the blank of the body 20 is formed by attaching a plurality of prepregs to a mold assembly such that the plurality of prepregs are laminated. Specifically, the connector 223 may be bonded to the prepregs, or the connector 223 may be covered by the prepregs.

The connector 223 includes a female thread 224. The connector 223 is located approximately at the center of the sole 22 in the toe-heel direction, and is located on the face 10 side of the sole 22 in the face-back direction. For example, titanium, a titanium alloy, aluminum, an aluminum alloy, tungsten, a tungsten alloy, stainless steel, or the like may be used as the material of the connector 223.

FIG. 21 is a cross-sectional view (part 1) of the golf club head 1E according to the sixth embodiment. In FIG. 21, the rod 90 is attached to the connector 223. The rod 90 illustrated in FIG. 21 is attachable to and detachable from the connector 223. For example, the rod 90 includes a head 91, a male thread 92, a cylindrical portion 93, and a cap 94. The male thread 92 is provided on one side of the head 91 concentrically with the head 91. The cylindrical portion 93 is provided on one side of the male thread 92 concentrically with the head 91 and the male thread 92. The tip side of the cylindrical portion 93 is reduced in diameter and is covered by the cap 94.

For example, a metallic material such as titanium, a titanium alloy, aluminum, tungsten, a tungsten alloy, stainless steel, or a ferrous metal may be used as the material of each of the head 91, the male thread 92, and the cylindrical portion 93. For example, a non-metallic material such as a resin, rubber, or a fiber-reinforced resin may be used as the material of the cap 94.

The head 91 of the rod 90 may be provided with a hexagonal groove, for example. The male thread 92 of the rod 90 can be screwed into the female thread 224 of the connector 223 by inserting the tip of a hex wrench or the like into the groove of the head 91 of the rod 90 and causing the rod 90 to rotate. The rod 90 is screwed into the connector 223 such that the rod 90 extends from the recessed portion 222 toward the back surface of the face 10, and the cap 94 contacts the back surface of the face 10.

That is, when the rod 90 is attached to the connector 223, the cylindrical portion 93, which is a metallic member, indirectly contacts the back surface of the face 10 via the cap 94, which is a non-metallic member. In other words, the total length of the rod 90 and the position of the connector 223 are designed such that the cap 94 at the tip side of the rod 90 contacts the back surface of the face 10.

The rod may be configured as illustrated in FIG. 22. FIG. 22 is a cross-sectional view (part 2) of the golf club head 1E according to the sixth embodiment. In FIG. 22, a rod 90A is attached to the connector 223. The rod 90A illustrated in FIG. 22 is attachable to and detachable from the connector 223. The rod 90A differs from the rod 90 in that the rod 90A does not include the cap 94. In addition, because the cap 94 is not included, the tip side of the cylindrical portion 93 is not reduced in diameter.

In FIG. 22, when the rod 90A is attached to the connector 223, the tip of the cylindrical portion 93 of the rod 90A contacts the back surface of the face 10. In other words, the total length of the rod 90A and the position of the connector 223 are designed such that the tip of the cylindrical portion 93 of the rod 90A contacts the back surface of the face 10.

As described above, the tip of the rod 90 or the rod 90A contacts the back surface of the face 10, thereby restricting the deformation of a contact portion between the face 10 and the rod 90 or the rod 90A. That is, the rod 90 and the rod 90A each function as a reinforcing member that restricts the local deformation of the face 10. The tip of the rod 90 or the rod 90A is tapered so as to make point contact with the back surface of the face 10, thus preventing the deformation of the face 10 from being excessively restricted.

The tip of the rod 90 or the rod 90A may contact the back surface of the face 10 so as not to press the back surface of the face 10 in a natural state, or may contact the back surface of the face 10 so as to press the back surface of the face 10 toward the face surface 10 f side. In addition, the degree of pressing the back surface of the face 10 may be adjusted in accordance with the degree of tightening of the male thread 92 to the connector 223. If the male thread 92 is tightened to the maximum extent, the distal end of the rod 90 or the rod 90A may slightly displace the back surface of the face 10 toward the face surface 10 f side.

With regard to the rigidity distribution of the face 10, restricting the deformation of the contact portion between the face 10 and the rod 90 or the rod 90A causes the rigidity from the center portion to the upper portion of the face 10 to be relatively low and causes the rigidity of the lower portion of the face 10 to be relatively high. That is, the upper portion of the face 10 readily deflects toward the back side by the impact of a golf ball. Accordingly, the launch angle of the golf ball can be further increased.

Further, the weight of the rod 90 or the rod 90A causes the center of gravity of the golf club head if to be located on the face 10 side. Accordingly, the amount of backspin of a golf ball tends to be reduced, and thus the maximum flight distance of the golf ball can be increased. That is, the rod 90 or the rod 90A may also function as a threaded weight member.

As described above, in the golf club head 1E, at least the sole 22 of the body 20 is formed by laminating layers of a fiber-reinforced resin. Therefore, the connector 223 made of metal can be readily embedded into the sole 22. Further, the rod 90 or the rod 90A is attached to the connector 223 such that the tip of the rod 90 or the rod 90A contacts the back surface of the face 10, thereby allowing the deformation of the face 10 to be restricted. The upper limit of the resilience of the face 10 is defined by the official rules of golf. However, by causing the tip of the rod 90 or the rod 90A to contact the back surface of the face 10 such that the deformation of the face 10 is restricted, the resilience of the face 10 can be intentionally reduced. As a result, the golf club head 1C can be designed to have a higher resilience over a wider range than conventional designs.

Further, as described above, the rod 90 or the rod 90A is attached to the connector 223 such that the tip of the rod 90 or the rod 90A contacts the back surface of the face 10, thereby allowing the deformation of the face 10 to be restricted. Accordingly, the upper portion of the face 10 readily deflects toward the back side by the impact of a golf ball, and thus the launch angle of the golf ball can be further increased. Further, if the crown 21 is formed by laminating layers of a fiber-reinforced resin, the crown 21 is more readily deflected, and as a result, an initial velocity can be increased as compared to the related art.

In the above, an example in which the rod 90 or the rod 90A is attached to the connector 223 has been described. However, instead of the rod 90 or the rod 90A, a threaded weight member that is exposed to the outside of the golf club head 1E may be attached to the connector 223. Similar to the rods 90 and 90A, the weight member can be configured to include a male thread; however, the tip of the weight member does not necessarily contact the face. Further, a plurality of weight members having different weights may be prepared, and the position of the center of gravity of the golf club head 1F can be adjusted by varying a weight member attached to the connector 223. Further, a plurality of connectors may be provided in the sole 22, and two or more weight members may be attached to the connectors.

Accordingly, in the golf club head 1E, the crown 21, the sole 22, and the hosel chamber 23 are formed by laminating layers of a fiber-reinforced resin, thus allowing additional weight to be readily secured as compared to conventional golf club heads. As a result, the additional weight can be added to a rod or a weight member.

Seventh Embodiment

A seventh embodiment depicts a golf club head in which the rigidity of the crown and the rigidity of the sole are controlled. In the seventh embodiment, descriptions of elements identical to those in the above-described embodiment may be omitted.

FIG. 23 is a plan view of a golf club head 1F according to the seventh embodiment. FIG. 24 is a partially enlarged view of the golf club head 1F when viewed from the inner surface of the crown 21 according to the seventh embodiment. As illustrated in FIG. 23 and FIG. 24, in the golf club head 1F, at least the crown 21, the sole 22, and the hosel chamber 23 of the body 20 are formed by laminating layers of a fiber-reinforced resin. The crown 21 includes three thin slits 211.

The slits 211 may be recessed portions that are elongated to partially extend in the toe-heel direction and are recessed from the inner surface of the crown 21 toward the outer surface of the crown 21. The slits 211 may be arranged at predetermined intervals. The slits 211 serve as rigidity control portions that decrease the flexural rigidity mainly in the face-back direction while reducing the influence on the flexural rigidity in the toe-heel direction.

Each of the slits 211 has a width W1, for example, greater than or equal to 1.0 mm and less than or equal to 10.0 mm and preferably greater than or equal to 2.0 mm and less than or equal to 5.0 mm. The distance S1 between two adjacent slits 211 may be, for example, greater than or equal to 1.0 mm and less than or equal to 20.0 mm and preferably greater than or equal to 3.0 mm and less than or equal to 8.0 mm. Each of the slits 211 may have a depth, for example, greater than or equal to 0.1 mm and less than or equal to 1.0 mm and preferably greater than or equal to 0.2 mm and less than or equal to 0.4 mm. Each of the slits 211 may have a length L1, for example, greater than or equal to 10.0 mm and less than or equal to 120.0 mm and preferably greater than or equal to 40.0 mm and less than or equal to 80.0 mm.

In FIG. 23, the three slits 211 are provided; however, this is merely an example. At least one slit 211 may be provided, and preferably, a plurality of slits 211 may be provided. Any number of slits can be provided depending on the required rigidity. As the number of slits 211 increases, the rigidity of the crown 21 decreases as long as the slits 211 have the same width, length, and depth.

The crown 21 may be formed by laminating three layers of prepregs as illustrated in FIG. 25 while heating and applying pressure to the prepregs. However, the crown 21 may be formed by laminating more than three layers of prepregs.

In FIG. 25, unidirectional (UD) prepregs in which reinforcing fibers are unidirectionally oriented and impregnated with a resin may be used as prepregs 51 and 53, which are located at the top and the bottom of the crown 21. The fibers in the prepregs 51 and 53 may be oriented approximately in the toe-heel direction. However, UD prepregs in which fibers are oriented to be inclined with respect to the toe-heel direction, or prepregs in which reinforcing fibers are woven vertically and horizontally and impregnated with a resin may also be used as the prepregs 51 and 53.

As the prepreg 52 sandwiched between the prepregs 51 and 53, a UD prepreg in which reinforcing fibers are unidirectionally oriented and impregnated with a resin may be used. The fibers in the prepreg 52 are oriented approximately in the face-back direction. The prepreg 52 is provided with three slits 521. When the prepregs 51 through 53 are processed, the slits 521 function as the slits 211.

As described above, the UD prepreg in which the fibers are oriented approximately in the face-back direction is used as the prepreg 52, and the slits 521 elongated to extend in the toe-heel direction are formed in the prepreg 52. With this configuration, the flexural rigidity mainly in the face-back direction can be decreased while reducing the influence on the flexural rigidity in the toe-heel direction.

FIG. 26 is a bottom view of the golf club head 1F according to the seventh embodiment. FIG. 27 is a front view of the body of the golf club head 1F according to the seventh embodiment. As illustrated in FIG. 26 and FIG. 27, the sole 22 includes two ribs 221. The two ribs 221 may be formed of a fiber-reinforced resin and arranged to intersect with each other when viewed in the crown-sole direction. The ribs 221 may be formed of the same fiber-reinforced resin as the sole 22. The ribs 221 serve as rigidity control portions that increase the flexural rigidity in the face-back direction. Carbon fibers of the fiber-reinforced resin constituting the sole 22 are preferably oriented in directions approximately the same as the extending directions of the ribs 221.

The two ribs 221 are projecting portions that are elongated to extend from the back surface side of the face 10 toward the back end 25 and inclined with respect to a plane P. The plane P is perpendicular to a horizontal ground plane on which the golf club head 15 rests at a predetermined lie angle and a predetermined loft angle, and includes an axis that extends from the center of the face 10 in a direction normal to the face 10. Viewing in the crown-sole direction means viewing in a direction normal to the horizontal ground plane on which the golf club head 15 rests at the predetermined lie angle and the predetermined loft angle.

When viewed in the crown-sole direction, inclination angles θ1 and θ2 of the two ribs 221 with respect to the plane P may be, for example, greater than or equal to 15 degrees and less than or equal to 45 degrees, and are preferably greater than or equal to 25 degrees and less than or equal to 35 degrees.

When viewed in the crown-sole direction, an intersection C of the two ribs 221 is preferably positioned so as to overlap with the plane P. By positioning the two ribs 221 in this manner, the rigidity of a part of the sole 22 can be readily increased.

Each of the ribs 221 has a width W2, for example, greater than or equal to 0.5 mm and less than or equal to 3.0 mm and preferably greater than or equal to 1.0 mm and less than or equal to 2.0 mm. Each of the ribs 221 has a height, for example, greater than or equal to 0.5 mm and less than or equal to 10 mm and preferably greater than or equal to 2.0 mm and less than or equal to 6.0 mm. Each of the ribs 221 has a length L2, for example, greater than or equal to 30.0 mm and less than or equal to 120.0 mm and preferably greater than or equal to 60.0 mm and less than or equal to 80.0 mm.

In the examples of FIG. 26 and FIG. 27, two ribs 221 are provided; however, this is merely an example. One or more ribs 221 may be provided depending on the required rigidity. For example, a single rib 221 that extends in a straight line or a curved line in any direction may be provided. If a plurality of ribs 221 are provided, the plurality of ribs 221 do not necessarily intersect with each other. For example, two or more ribs 221 may be arranged in parallel approximately in the face-back direction, or may be arranged in a V shape that opens toward the face side. Alternatively, one or more ribs 221 that are approximately parallel to the face-back direction and one or more ribs 221 that are approximately perpendicular to the face-back direction may be arranged to intersect with each other.

In order to form such a slit 211 and a rib 221, the slit may be formed in a portion of prepregs and a portion of the prepregs may be formed in a rib shape before the prepregs are laminated when a golf club head is manufactured by the method described in the first embodiment.

As described above, in the golf club head 1F, at least the crown 21, the sole 22, and the hosel chamber 23 of the body 20 are formed by laminating layers of a fiber-reinforced resin. Accordingly, the rigidity of the crown 21 and the rigidity of the sole 22 can be readily adjusted in contrast to when the crown 21 and the sole 22 are formed of a metal such as titanium. The ball striking performance of the golf club head 1F is improved by controlling the rigidity of the crown 21 and the rigidity of the sole 22, which are formed of a fiber-reinforced resin. Specifically, while the slits 211 decrease the flexural rigidity in the face-back direction of the crown 21, the ribs 221 increase the flexural rigidity in the face-back direction of the sole 22. Accordingly, the crown 21 readily deflects by the impact of a golf ball, and thus the launch angle of the golf ball can be increased.

For a golf club head in which the body 20 is formed of a metal such as titanium, there may be many limitations depending on the manufacturing method (casting or forging). Particularly, if the thickness of a predetermined portion is increased in order to partially increase the flexural rigidity, the weight of the predetermined portion would be increased. As a result, the degree of freedom in designing functions of the head would be reduced. Similarly, if the thickness of a predetermined portion is decreased in order to partially decrease the flexural rigidity, the structural strength of the head would be reduced. As a result, the head would be susceptible to damage from impact when hitting a ball. Therefore, it would not be easy to decrease the rigidity of a crown 21 and increase the rigidity of a sole 22 while reducing the influence on other elements. Thus, rigidity control would be limited to a narrow range.

In contrast, in the above-described manufacturing method in which a fiber-reinforced resin is used as the material of the body 20, prepregs including fibers having various elastic moduli may be used, prepregs having different ratios of fibers to a resin may be used, prepregs may be formed in various shapes, or prepregs may be combined with a different material (such as a metal wire, metal mesh, or a blowing agent). Accordingly, rigidity can be designed in a wider range, not achievable if the body 20 were formed of a metal such as titanium. As a result, golf clubs with suitable characteristics can be provided to golfers with different swing types.

In the present embodiment, the slits 211 are adopted as rigidity control portions that decrease the flexural rigidity mainly in the face-back direction while reducing the influence on the flexural rigidity in the toe-heel direction, and the ribs 221 are adopted as rigidity control portions that increase the flexural rigidity in the face-back direction. However, the present invention is not limited thereto, and the slits 211 are not necessarily formed. For example, instead of the slits 211, a low elasticity material may be provided, or a prepreg sheet cut in a rectangular shape and having slit-like openings may be provided. Further, metal wires or metal mesh may be adopted instead of the ribs 221. Alternatively, the ribs 221 may be metal pieces, or may be metal pieces covered by a fiber-reinforced resin. Examples of low elasticity materials include resins, rubber, and fiber-reinforced resins.

In the present embodiment, the rigidity control portions that decrease the flexural rigidity mainly in the face-back direction while reducing the influence on the flexural rigidity in the toe-heel direction are provided in the crown 21, and the rigidity control portions that increase the flexural rigidity in the face-back direction are provided in the sole 22. However, the present invention is not limited thereto, and rigidity control portions that increase the flexural rigidity mainly in the face-back direction while reducing the influence on the flexural rigidity in the toe-heel direction may be provided in the crown 21, and rigidity control portions that decrease the flexural rigidity mainly in the face-back direction while reducing the influence on the flexural rigidity in the toe-heel direction may be provided in the sole 22. In this case, the effect for preventing a ball from being hit too high can be provided.

The seventh embodiment can be implemented simultaneously with any other modifications. For example, the golf club head 1F may be provided with a metal hosel and a rod.

Eighth Embodiment

An eighth embodiment depicts examples of golf club heads each including a body having a different configuration. In the eighth embodiment, descriptions of elements identical to those in the above-described embodiments may be omitted.

FIG. 28 is an exploded perspective view of a golf club head 1G according to the eighth embodiment. As illustrated in FIG. 28, the golf club head 1G has a hollow structure in which the face 10 is integrated with a body 30.

The body 30 includes a first member 31 located on the crown side and a second member 32 located on the sole side. The first member 31 and the second member 32 are combined to form the body 30, and the body 30 and the face 10 are further combined to form the golf club head 1G.

For example, the golf club head 1G is manufactured by the method as described below. First, a mold assembly, constituted by an upper mold and a lower mold that can be assembled and disassembled, is prepared. A plurality of layers of prepregs formed of a fiber-reinforced resin are prepared, and the prepregs are attached to the upper mold so as to be laminated. In this manner, the first member 31 is formed. Next, a plurality of layers of prepregs formed of a fiber-reinforced resin are prepared, and the prepregs are attached to the lower mold so as to be laminated. In this manner, the second member 32 is formed.

Next, the upper mold and the lower mold are assembled such that the first member 31 is coupled to the second member 32. In this manner, a blank of the body 30 of the golf club head 1G is formed.

Next, the mold assembly including the blank of the body 30 is placed into a bag. The bag is placed in an openable sealed container, and heat is applied by the heating mechanism while a vacuum is created by the pneumatic mechanism. In this manner, the prepregs formed of the fiber-reinforced resin, which constitute the blank of the body 30, are cured by a cross-linking reaction. After the heating, the body 30 is bonded to the preformed face 10 to form a semi-finished golf club head. The semi-finished golf club head is deburred and subjected to surface finishing to obtain the golf club head 1G.

FIG. 29 is an exploded perspective view of a golf club head 1H according to the eighth embodiment. As illustrated in FIG. 29, the golf club head 1H has a hollow structure in which the face 10 is integrated with a body 40.

The body 40 includes a first member 41 located on the face side and a second member 42 located on the back side. The first member 41 and the second member 42 are combined to form the body 40, and the body 40 and the face 10 are further combined to form the golf club head 1H.

For example, the golf club head 1H may be manufactured by a method as described below. First, a mold assembly, constituted by a front mold and a back mold that can be assembled and disassembled, is prepared. A plurality of layers of prepregs, formed of a fiber-reinforced resin, are prepared, and the prepregs are attached to the front mold so as to be laminated. In this manner, the first member 41 is formed. Next, a plurality of layers of prepregs formed of a fiber-reinforced resin are prepared, and the prepregs are attached to the back mold so as to be laminated. In this manner, the second member 42 is formed.

Next, the front mold and the back mold are assembled such that the first member 41 and the second member 42 are coupled together. In this manner, a blank of the body 40 of the golf club head 1H is formed.

Next, the mold assembly including the blank of the body 40 is placed into a bag. The bag is placed in an openable sealed container, and heat is applied by the heating mechanism while a vacuum is created by the pneumatic mechanism. In this manner, the prepregs formed of the fiber-reinforced resin, which constitute the blank of the body 40, are cured by a cross-linking reaction. After the heating, the body 40 is bonded to the preformed face 10 to form a semi-finished golf club head. The semi-finished golf club head is deburred and subjected to surface finishing to obtain the golf club head 1H.

As described above, an integrally formed body may be used as described in the golf club heads 1 to 1F, or a composite body may be used as described in the golf club heads 1G and 1H.

According to an aspect of the present disclosure, a golf club head at least partially formed of a fiber-reinforced resin can be reduced in weight and increased in volume while also improving ball striking performance.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the particulars of the above-described embodiments. Variations and modifications may be applied to the above-described embodiments without departing from the scope of the present invention. 

What is claimed is:
 1. A golf club head having a hollow structure, the golf club head comprising: a face; a body including at least a crown, a sole, and a hosel chamber, the crown, the sole, and the hosel chamber including laminated layers of a fiber-reinforced resin; and a weight portion formed of a material having a specific gravity greater than specific gravities of the crown and of the sole, and disposed inward relative to a head shell, wherein a head volume is greater than or equal to 450 cc and less than or equal to 470 cc, wherein a head weight is less than or equal to 200 g, wherein an average thickness of each of the crown and the sole is greater than or equal to 0.7 mm, and wherein a weight of the weight portion is greater than or equal to 20 g, and the weight portion is attached to one or both of the crown and the sole.
 2. The golf club head according to claim 1, wherein a characteristic time (CT), corresponding to a coefficient of restitution of the face, is less than or equal to 257 μs.
 3. The golf club head according to claim 1, wherein the head weight is greater than or equal to 180 g, and the weight of the weight portion is greater than or equal to 30 g and less than or equal to 55 g.
 4. The golf club head according to claim 1, wherein the weight portion is not exposed to inside of and outside of the body.
 5. The golf club head according to claim 1, wherein the weight portion has a first surface and a second surface, the first surface contacting the head shell and the second surface not contacting the head shell, at least one layer of a fiber-reinforced resin is provided on the second surface, and the at least one layer of the fiber-reinforced resin contacts one or both of an inner surface of the crown and an inner surface of the sole.
 6. The golf club head according to claim 1, wherein a maximum head height is greater than or equal to 60 mm, and a maximum head width is greater than or equal to 112 mm.
 7. The golf club head according to claim 1, wherein the weight of the weight portion is 20% or more of the head weight.
 8. The golf club head according to claim 1, wherein the sole includes a rib formed of a fiber-reinforced resin.
 9. A golf club head having a hollow structure, the golf club head comprising: a face; a body including at least a crown, a sole, and a hosel chamber, the crown, the sole, and the hosel chamber including laminated layers of a fiber-reinforced resin; and a weight portion formed of a material having a specific gravity greater than specific gravities of the crown and of the sole, and disposed inward relative to a head shell, wherein a head volume is greater than or equal to 450 cc and less than or equal to 470 cc, wherein a head weight is less than or equal to 180 g, wherein an average thickness of each of the crown and the sole is greater than or equal to 0.7 mm, and wherein a weight of the weight portion is greater than or equal to 10 g, and the weight portion is attached to one or both of the crown and the sole.
 10. The golf club head according to claim 9, wherein a characteristic time (CT), corresponding to a coefficient of restitution of the face, is less than or equal to 257 μs.
 11. The golf club head according to claim 9, wherein the head weight is greater than or equal to 160 g, and the weight of the weight portion is less than or equal to 35 g.
 12. The golf club head according to claim 9, wherein the weight portion is not exposed to inside of and outside of the body.
 13. The golf club head according to claim 9, wherein the weight portion has a first surface and a second surface, the first surface contacting the head shell and the second surface not contacting the head shell, at least one layer of a fiber-reinforced resin is included at the second surface, and the at least one layer of the fiber-reinforced resin contacts one or both of an inner surface of the crown and an inner surface of the sole.
 14. The golf club head according to claim 9, wherein a maximum head height is greater than or equal to 60 mm, and a maximum head width is greater than or equal to 112 mm.
 15. The golf club head according to claim 9, wherein a center-of-gravity angle is greater than or equal to 15 degrees and less than or equal to 40 degrees.
 16. The golf club head according to claim 9, wherein a center-of-gravity distance is greater than or equal to 35 mm and less than or equal to 45 mm.
 17. The golf club head according to claim 9, wherein a value obtained by dividing the weight of the weight portion by the head weight is greater than or equal to 0.09 and less than or equal to 0.19.
 18. The golf club head according to claim 9, wherein a value obtained by dividing a center-of-gravity distance by the head weight is greater than or equal to 0.21.
 19. The golf club head according to claim 9, wherein a value obtained by dividing a center-of-gravity angle by the head weight is greater than or equal to 0.13 and less than or equal to 0.17.
 20. The golf club head according to claim 9, wherein the sole includes a rib formed of a fiber-reinforced resin. 